Microwave-Assisted SPME/On-Fiber Derivatization of Chromium(III) in Water Followed by GC-MS Analysis

A simple and rapid SPME/on-fiber derivatization procedure coupled with GC-MS for the analysis of Cr(III) in water has been developed. Aqueous Cr(III) was simultaneously extracted and on-fiber derivatized to the volatile chromium trifluoroacetylacetonate (Cr(TFA)₃) by using a polyimide SPME fiber precoated with the derivatizing reagent, 1,1,1-trifluoroacetylacetone (HTFA). With the aid of microwave irradiation, extraction/derivatization of Cr(III) at ng mL⁻¹ level could be accomplished in 90 s. The Cr(TFA)₃-bearing fiber was directly injected into a GC-MS for analysis. The two Cr(TFA)₃ isomers extracted could be efficiently separated in 6 min. Linearity (R ² = 0.9978, n = 7) over the concentration range 0.2-200 ng mL⁻¹ Cr was obtained and the LOD (3σ, n = 5) was 0.06 ng mL⁻¹ Cr. The RSD was 4.7% at 2 ng mL⁻¹ Cr (n = 7). Applicability of this method to water analysis was examined by analyzing the chromium content in a reference standard water sample and two river water samples.